VisualSVN - VisualSVN - Subversion plugin for Visual Studio
TortoiseSVN - The coolest interface to (Sub)version control
Xversion - Super easy enterprise class version control.
SnailSVN - Similar to Tortoise SVN for Windows but integrated into Finder
Slik SVN - SlikSVN is a free subversion client for the command line.
RapidSVN - CollabNet, Facilitating Collaborative Software Development